[fs.usda.gov] Habitat, Cushion Plant: Twinflower sandwort, also called alpine sandwort, is found in alpine tundra throughout the West. The word tundra comes from the Finnish word “tunturia” which means treeless land. Alpine tundra is found on mountain tops above the elevation where trees will grow. At these elevations, often above 11,000 feet, the summers are short, freezing temperatures are possible at any time, there are harsh drying winds, and the sunlight is intense. The soils tend to be rocky, dry, and nutrient poor. Twinflower sandwort is a cushion plant, which is a term that describes the growth form of many alpine tundra plants. Apparently, this growth form works well to protect plants from alpine weather extremes because it has been adopted by many unrelated alpine plants. The cushion shape helps protect tender parts from frost and high winds, helps retain moisture, and holds in heat. Studies have shown that the temperature within a plant cushion can be up to 10 centigrade degrees higher than the ambient temperature. (link added by Mary Ann Machi)